A variety of types of structural beams are used in non-residential construction. Some examples include fabricated wooden girders, laminated wood beams, and reinforced concrete beams. By far, the most commonly used material is structural steel of various cross sections, such as "I"-section, "H"-section, "C"-section, "Z"-section, and channel section. These structural steel shapes are most commonly manufactured by hot or cold rolling processes and generally provide a relatively heavy beam for a given load carrying capacity.
Structural sections fabricated from sheet steel are used in some construction applications. For example, it is now a common practice to utilize fabricated steel studs, particularly in non-residential construction. These are generally made from galvanized steel sheet, cold-rolled into a "C"-section or channel section. Furthermore, corrugated or fluted steel sheets are widely used in flooring and roofing applications.
Certain other fabricated structural shapes are known in the prior art. For example, FIG. 1 illustrates a prior art structural shape fabricated from sheet steel. Beam 1 comprises a web portion 2 and opposing head portions 3 and 4. As can be clearly seen in the illustration, beam 1 can be easily fabricated from a single flat sheet of steel by rolling or otherwise folding the sheet longitudinally. It should be noted that edges 5 and 6 of the sheet are folded back towards web portion 2, but are not fastened or otherwise secured thereto. A prior art beam such as beam 1 has a very limited load bearing capability.
It is one of the objects of the present invention to provide a fabricated structural beam that has a load carrying capability comparable to that of conventional hot or cold rolled structural steel sections, but which is light in weight compared to a conventional section of equal load carrying capability.